The use of petroleum hydrocarbons as a fuel source is ubiquitous in society. Consequently, petroleum hydrocarbon products are stored and handled in great quantities. One risk associated with the storage and handling of petroleum hydrocarbons is the potential for spillages during handling or the potential for leakage during storage. Due to the negative environmental impact associated with spills and leakages of petroleum hydrocarbons, rules have been established at the local, state and federal levels. These rules primarily focus on preventing petroleum hydrocarbon releases to the environment from occurring. These rules also have provisions that require the responsible party to remediate petroleum hydrocarbon releases to the environment.
In the field of petroleum hydrocarbon remediation from soil, there are two basic approaches: applying a treatment technique to soil in place (in-situ), or applying a treatment technique to excavated soil (ex-situ). There are advantages and disadvantages for each approach and the selection of the approach is based on the site-specific circumstances of each petroleum hydrocarbon release.
In-situ thermal desorption technologies can include techniques that involve applying heat and vacuum simultaneously to subsurface soils to vaporize volatile contaminates in the soil. Processes of vaporizing of contaminates can include evaporation into the subsurface air stream, steam distillation into the water vapor stream, boiling, oxidation, and/or pyrolysis. The vaporized water, contaminants, and organic compounds are drawn by the vacuum in a counter-current direction to the flow of heat into the source of vacuum.
Ex-situ thermal desorption technologies can include techniques that involve mechanical agitation of the soil during the heating process, which involve mechanical agitation and operate in a continuous process where the soil is continuously introduced to the process and is mechanically moved through the process apparatus until treatment is complete, and then is continuously discharged to a container for disposal or re-use.
Alternately, the soil can be treated in a static configuration of an ex-situ thermal desorption system, in which a given amount of soil is introduced to the treatment chamber. The soil configurations can include pile arrangement and container arrangements.
Nearly all the prior art processes use combustion of fossil fuel as a heat source. This can have the consequence of forming products of incomplete combustion, oxides of nitrogen, and other greenhouse gases as a by-product. Combustion also has the potential to add unburned hydrocarbons to the process exhaust gas if strict control of the combustion process is not maintained.
There is a need for an ex-situ static process that is labor, time and energy efficient in the treatment process, and is environmentally friendly.